Various techniques have been reported for use of microorganisms, such as bacteria and viruses, in transferring substances, e.g., nucleic acids and proteins, to cells and organisms. Various techniques have also been reported for detection of microorganisms in samples and in organisms, including animals. Many such techniques involve incorporation of nucleic acid encoding a foreign protein (e.g., a detectable marker or protein of interest for transfer to a sample) into the microorganism. The amount of foreign protein or detectable signal is related to, and thus can be dependent on, the amount of the microorganism present in the sample, the extent to which the microorganism is able to increase in number, or replicate, in the sample and the degree of expression of the foreign marker. Additionally, for some microorganisms, toxicity of the microorganism in the sample, particularly an animal, can necessitate limiting the amount of the microorganism that is provided to the sample.
Accordingly, there is a need for alternative methods and compositions to provide for enhanced detection of microorganisms in a sample, such as an animal, potentially allowing for rapid growth in the sample, at lower initial concentrations, reduced toxicities and with decreased reliance on foreign protein expression.